Twenty-one tonghaosu analogs were synthesized via hydroamination or selective reduction of the endocyclic double bond of the corresponding dienol spiroketals. Structures of all the new compounds were confirmed by H-1 NMR, IR, MS, HREIMS or elemental analysis. Their antifeedant activity against large white butterfly (Pieris brassicae L) and larvicidal activity toward mosquito (Culex quinquefasciatus Say) were examined. Some of them exhibited antifeeding activities comparable to or stronger than tonghaosu Z-1. Based on the activity data, the preliminary structure-activity relationship was also discussed, which might be instructive for finding out lead compounds with better bioactivities in the future.